Air/fuel ratio controllers are used to regulate the flow (particularly the pressure) of fuel fed to internal combustion engines. Some of these air/fuel ratio controllers are incorporated in a feedback control loop for the engine in order to maintain a constant percentage of oxygen in the engine's exhaust. By maintaining oxygen exhaust gas at a constant level, undesirable emissions from the engine are reduced to a minimal level. Also, catalytic converters in the engine's exhaust system are designed to operate at certain oxygen content levels. By maintaining a certain oxygen content, the converter operates in its optimal range. The air/fuel ratio controller is used in conjunction with an oxygen sensor and a temperature sensor, which are both exposed to the exhaust gas emitted by the internal combustion engine. After filtering the electronic signals generated by these sensors, prior art air/fuel ratio controllers compensated the oxygen signal in a linear manner by monitoring the temperature. In other words, the prior art devices were designed to operate under the assumption that above a certain cut-off temperature, the oxygen sensor varied linearly with temperature. In one prior art device, after the linear compensation of the oxygen content signal, that signal was fed into a proportional, integral, derivative control circuit whose output was coupled to a valve driver. The control signal output by the valve driver was fed directly to the fuel pressure regulator for the internal combustion engine.